Bottom Line:
However, conventional electrodes are not appropriate for long-term measurements and are easily influenced by the environment, so the range of applications of sEMG is limited.The results show that the proposed electrode is robust to perspiration and can maintain a high-quality measuring ability for over 8 h.The proposed electrode also has high selectivity for motion compared with a commercial wet electrode and dry electrode.

ABSTRACTSurface electromyography is widely used in many fields to infer human intention. However, conventional electrodes are not appropriate for long-term measurements and are easily influenced by the environment, so the range of applications of sEMG is limited. In this paper, we propose a flexible band-integrated, curved microneedle array electrode for robust long-term measurements, high selectivity, and easy applicability. Signal quality, in terms of long-term usability and sensitivity to perspiration, was investigated. Its motion-discriminating performance was also evaluated. The results show that the proposed electrode is robust to perspiration and can maintain a high-quality measuring ability for over 8 h. The proposed electrode also has high selectivity for motion compared with a commercial wet electrode and dry electrode.

Mentions:
The classification accuracy distribution is described in Figure 14 and Table 2. The accuracy of the MNA electrode was significantly higher than that of the commercial electrodes, where the accuracy was defined as average, best or worst. Thus, the proposed electrode achieved higher discriminating performance for a complex muscle group. Although the electrode placement and the size of both electrodes were similar, the wet electrode produced more crosstalk noise, because the diffused electrolyte increased the effects of the activation of nearby muscles. As described in the confusion matrix (Figure 15b), the wet electrode showed a higher error rate between forward motion and backward motion, indicating that the measured signals in both cases were difficult to distinguish. Similarly, the dry electrode measured signals from the skin surface only, so the dry electrode produced more crosstalk noise than the MNA electrode (Figure 15c). However, the proposed electrode showed a higher true rate, as shown in Figure 15a. The one-way analysis of variance showed that there was a significant difference (p < 0.001). The selectivity depends on the electrode contact conditions, so the proposed electrode achieved higher muscle selectivity, because the tiny needles contacted locally with the conductive tissue in the inner skin layers with no medium. Other subjects showed a similar tendency, except Subject 2, as described in Figure 16.

Mentions:
The classification accuracy distribution is described in Figure 14 and Table 2. The accuracy of the MNA electrode was significantly higher than that of the commercial electrodes, where the accuracy was defined as average, best or worst. Thus, the proposed electrode achieved higher discriminating performance for a complex muscle group. Although the electrode placement and the size of both electrodes were similar, the wet electrode produced more crosstalk noise, because the diffused electrolyte increased the effects of the activation of nearby muscles. As described in the confusion matrix (Figure 15b), the wet electrode showed a higher error rate between forward motion and backward motion, indicating that the measured signals in both cases were difficult to distinguish. Similarly, the dry electrode measured signals from the skin surface only, so the dry electrode produced more crosstalk noise than the MNA electrode (Figure 15c). However, the proposed electrode showed a higher true rate, as shown in Figure 15a. The one-way analysis of variance showed that there was a significant difference (p < 0.001). The selectivity depends on the electrode contact conditions, so the proposed electrode achieved higher muscle selectivity, because the tiny needles contacted locally with the conductive tissue in the inner skin layers with no medium. Other subjects showed a similar tendency, except Subject 2, as described in Figure 16.

Bottom Line:
However, conventional electrodes are not appropriate for long-term measurements and are easily influenced by the environment, so the range of applications of sEMG is limited.The results show that the proposed electrode is robust to perspiration and can maintain a high-quality measuring ability for over 8 h.The proposed electrode also has high selectivity for motion compared with a commercial wet electrode and dry electrode.

ABSTRACTSurface electromyography is widely used in many fields to infer human intention. However, conventional electrodes are not appropriate for long-term measurements and are easily influenced by the environment, so the range of applications of sEMG is limited. In this paper, we propose a flexible band-integrated, curved microneedle array electrode for robust long-term measurements, high selectivity, and easy applicability. Signal quality, in terms of long-term usability and sensitivity to perspiration, was investigated. Its motion-discriminating performance was also evaluated. The results show that the proposed electrode is robust to perspiration and can maintain a high-quality measuring ability for over 8 h. The proposed electrode also has high selectivity for motion compared with a commercial wet electrode and dry electrode.